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Physic Principles > pulse echo instrumentation > Flashcards

pulse echo instrumentation Flashcards

1
Q 
what control could you adjust to improve the signal to noise ration on the image?
dynamic range
frame averaging
gray scale map
edge enhancement
receiver gain
A

frame averaging

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2
Q

the incoming raw echo signals must be compressed into a smaller dynamic range b/c:
wide DR results in inc display of electronic noise
wide DR does not allow dif. b/w echoes arriving from dif depths
display cannot accommodate wide DR of the incoming signals
existing wide DR significantly slows frame rate
wide DR compromised spatial res

A

display cannot accommodate wide DR of incoming signals
b/c the DR of the system electronics & display is less than that of the raw echo data, it must be compressed into usable range

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3
Q 
what type of imaging results in selective reception of freq that are 2x that of the transmitted freq?
color doppler
PW
tissue doppler
m-mode
tissue harmonic
A

tissue harmonics

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4
Q 
technique of frame averaging during real time acquisition is designed to:
reduce random noise
decrease pixel size
redistribute gray scale
enhance spatial res
increase frame rate
A 
reduce random noise
frame averaging (persistence) averages data in pixels over successive frames; slight movements of xducer or patient result in slight changes to specle pattern, so frame avg has the effect of smoothing image to reduce speckle
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5
Q 
selective reception of echoes generated within the body by nonlinear propogation describes:
compound imaging
tissue harmonics
speckle reduction
3d image
tomographic u/s image
A

tissue harmonic imaging

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6
Q 
a type of sonograpic imaging that transmits two pulses of opposite phase in rapid succession so they can be cancelled upon reception:
pulse inversion harmonics
compound imaging
specle reduction imaging
tomographic imaging
panoramic imaging
A

pulse inversion harmonics

effective method to filter out the fundamental freq (transmitted freq) and leave only the harmonic freq for display

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7
Q 
what can you do to improve the temporal res?
increase # of focal zones
increase depth
increase sector width
decrease acoustic scan line density
decrease acoustic power output
A

decrease the acoustic scan line density

which decreases the time required to create the image which results in increased frame rate

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8
Q

duty factor means:
fraction of time xducer is transmitting
fraction of time xducer is receiving
fraction of time b/w transmitted and received pulse
fraction of time b/w transmitted sound pulses
fraction of time required for round trip travel of sound pulse to 1 cm in tissue

A

fraction of time xducer is transmitting sound

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9
Q 
electronic steering is most commonly applied to which real time xducers?
annular
sequential linear
mechanical sector
phased
segmental linear
A

phased array

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10
Q 
which is the best choice to help demonstrate tissue boundaries that are not perpendicular to sound beam?
speckle reducing algorithm
spatial compoounding
persistence
panoramic imaging
TGC
A

spatical compounding

a method in which sound beam is steered in multiple directions by employing time delays

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11
Q

what is a disadvantage of a water path scanner?
reduces axial res
beam width perpendicular to image plane is inc, resulting in poor elevational res
bubbles in fluid can inhibit sound transmission in body
useful only with low freq
fluid path inc the MI

A

bubbles in fluid can inhibit sound transmission in body
although they reduce reverberation from shallow structures; they require vigorous maintenance to keep the fluid path completely filled at all times if only partially filled; air bubbles become trapped b/w xducer and probe

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12
Q 
what scanning mode doesn't rely on principle of echo ranging to determine interface location
m-mode
 transmission
PW
static b-mode
a mode
A

transmission

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13
Q 
what type of focusing is performed by delay circuitry upon reception?
dynamic receive focusing
elevational focusing
transmit focus
multizone transmit
mech focusing
A

dynamic receive focusing

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14
Q 
when you select compound imaging which artifact is less likely to be observed
refraction
shadowing 
enhancement 
acoustic speckle
all of the above
A

all of the above

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15
Q 
what is the typical farm rate for b mode real time imaging
1-9 kHz
10-50 Hz
100-200 MHz
200-300 Hz
.05-.9 Hz
A

10-50 HZ

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16
Q 
what is the advantage of using a 3d/4d xducer w/ automated sweep compared to traditional xducer w/ freehand sweep
measurement accuracy
spatial res
contrast res
larger field of view
greater scanning flexibility
A

measurement accuracy

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17
Q

whats the purpose of pre amplification of incoming signal
to decreased DR of signal
inc echo voltages before noise is induced through cable
reduce sensitivity to side lobes
reduce acoustic imped mismatch b/w the tissue and xducer
compensate for attenuation of beam w/ depth

A

inc echo volt. before noise is induced through cable

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18
Q 
The wavelength you obtain from an arterial stenosis demonstrates aliasing. if you increase the PRF to eliminate the aliasing, what artifact could be introduced?
multipath reflections
spectrum mirror image
prop speed error
range ambiguity
refraction
A

range ambiguity

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19
Q 
what system control determines the ant of amplification that occurs in the receiver?
gain
acoustic power output
rectification
PRF 
dynamic range
A

GAIN

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20
Q

you are imaging a 3d dataset that has anisotropic res. what does this mean?
spatial res is better than temp res
spatial res is = in all dimensions
contrast res is superior to spatial res
unequal res is present b/w imaging planes
elevation res and contrast res are the same

A

unequal res is present b/w imaging planes

isotropic res= spatial res is = in all dimesnsions
anisotropic res is the opposite

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21
Q 
what action would decrease frame rate?
inc PRF
inc acoustic scan line density
decrease sector width
decrease number of focal zones
decrease image depth
A

inc aoustic scan line density

temp res is determined by frame rate. as density of acoustic scan line inc lateral res inc but frame rate dec b/c it takes additional time to perform the pulse-listen sequences.

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22
Q 
what is the typical frame rate for b-mode real time imaging?
1-9 kHz
10-50 Hz
100-200 MHz
200-300 Hz
.05-.9 Hz
A

10-50 Hz

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23
Q 
if you inc the PRF & leave all other controls unchanged what happens?
lat res will improve
frame rate will inc
frame rate will dec
axial res will improve
freq will inc
A

frame rate will increase

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24
Q

in the scan converter, interpolation is performed to:
amplify reflected signal in comparison to background noise
dec dynamic range to a level that can be handled by monitor
amplify weak echo signals from deep structures to compensate for beam attenuation
fill in empty pixels that occur b/w acoustic scan lines
inc number of shades of gray in resulting image

A

fill in empty pixels that occur b/w acoustic scan lines
interpolation is necessary b/c there is not data available for all pixels in the scan converter matrix. as line density dec, more interpolation is needed to fill empty spaces

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25
Q 
frame averaging during imaging is designed to:
reduce random noise
dec pixel size
redistribute gray scale
enhance spatial res
inc frame rate
A

reduce random noise

aka persistence avgs the data in pixels over successive frames; it smoothes the image or reduces speckle

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26
Q 
what can you do to improve temp res?
inc number of focal zones
inc depth
inc sector width
dec acoustic scan line density
dec acoustic power output
A

dec acoustic scan line density

this dec the time required to create the image which increases the frame rate

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27
Q 
you are manipulating a vol dataset that was previously obtained on your pt. what is the max number of imaging planes that can be obtained ?
1
10
100
1000
there is no limit
A

there is no limit

vol. datasets can be manipulated to show an infinite number of imaging planes w/ many diff. images

28
Q 
you are imaging a fluid filled structure w/ equidistant horizontal bands appearing in the near field.  they have decreasing brightness with depth. what artifact is this?
slice thickness
side lobes
reverberation
comet tail
ring down
A

reverberation

29
Q 
what adjustment inc the DUTY FACTOR?
inc receiver gain
inc output power
inc PRF
inc scanning time
inc TGC
A

inc PRF
PRF= number of pulses emitted in 1 sec
DF= percentage of time that the u/s is being transmitted
as PRF inc, percentage of time the u/s is “on” inc.

30
Q 
when inc scanning depth, which is automatically dec by the system to avoid range ambiguity?
number of focal zones
sector width
PRF
PRP
PD
A

PRF

31
Q 
what artifact is from an array xducer due to energy that propagates from the xducer in a direction diff from the primary beam?
grating lobe
mirror image
reverberation
range ambiguity
acoustic enhancement
A

grating lobe

they are the same as side lobes but occur only with array xducers.

32
Q 
what artifact is the result of reverberation?
comet tail
acoustic speckle
beamwidth
refraction
all of the above
A

comet tail

common with metallic objects; occurs when sound bounces back and forth multiple times b/w two interfaces

33
Q 
what control can improve signal to noise ratio?
dynamic range
frame averaging
gray scale map
edge enhancement 
receiver gain
A

frame averaging

34
Q

the range equation describes the relationship b/w:
acoustic impede of 2 media
side lobe intensity b/w two crystals
round trip pulse travel time & dist to reflector
bandwidth & xducer freq
all of the above

A

round trip pulse travel time & dist to reflector

35
Q 
what effect will you see if you inc reject level?
inc # of shades of gray
dec low level echoes
dec frame rate
dec scanning depth
dec amplitude of brightest shade of gray
A

dec low level echoes

rejection is used to eliminate weak echo signals from display

36
Q 
which display mode is used to calculate dist measurements?
a mode
b mode
m mode
b-mode & m-mode
all of the above
A

all of the above

37
Q 
the range equation is used to determine:
reflector amplitude
reflector freq
reflector direction
reflector depth
reflector size
A

reflector depth
range equation:
d=1/2 ct
d=depth c=speed of sound in tissue t=round trip travel time

38
Q 
what advantage comes from using tissue harmonics?
improved contrast res
improved penetration
improved temp res
improved signal to noise ratio
increased bandwidth
A

improve contrast res

39
Q 
you inc imaging depth and scan line density. what does this result in?
reduced contrast res
reduced temp res
improved axial res
reduced lat res
all of the above
A

reduced temp res

40
Q 
what is not a function of the receiver:
amplification
rf to video conversion
demodulation
dynamic aperture
compression
A

dynamic aperture

it occurs in beam former and pulser

41
Q 
what mode does not rely on echo ranging to determine interface location?
mmode
PW
static b mode
transmission
b mode
A

transmission

42
Q 
number of images displayed per second in real time imaging:
PRF
PRP
frame rate
PD
pulse length
A

frame rate

43
Q 
what physical concept allows us to determine location of an interface by measuring the elapsed time b/w transmitted pulse u/s wave and detected echo?
huygens principle
shells law
doppler effect
echo ranging
none of the above
A

echo ranging

44
Q 
what technique would be most likely to produce grating lobes?
tomographic u/s imaging
3d imaging
beam steering
speckle reduction imaging
tissue harmonic imaging
A

beam steering

45
Q

using a xducer that produces a beam w/ very wide slice thickness. what problem might you encounter?
decreased penetration
partial volume artifact
increased near field reverberations in fluid structures
side lobes
decreased frame rate

A

partial volume artifact

aka slick thickness artifact

46
Q 
what system function is limited by the speed of sound in tissue?
demodulation
voltage amplitude
PRF
rectification
TGC
A

PRF

47
Q

which of the following describes an analog signal?
discrete values
fixed steps b/w values
levels are determined by bits
no analog signals exist in modern instruments
continuous variation of the signal is possible

A

continuous variation of the signal is possible

48
Q 
what is an advantage of a water path scanner?
penetration inc
temp res is improved
near field reverberations reduced
axial res improved
slice thickness reduced
A

near field reverberations are reduced

49
Q

performing a 3d sonogram and volume rate is 8 Hz what does this mean?
number of volumes displayed per sec
number of transmitted sound pulses per sec
number of received pulses per min
number of frames per vol
number of frames per sec

A

number of volumes displayed per sec

50
Q 
what component of the u/s system converts electric energy provided by pulser into acoustic pulses transmitted into patient?
transducer
 receiver
scan converter
memory
display
A

transducer

51
Q 
what is the main advantage of having a thin slice over image plane?
imrpoved frame rate
better axial res
dec vol avg
larger field of view
greater penetration
A

decreased volume averaging

52
Q 
what effect will you detect in the image if you inc the threshold?
inc image brightness
dec image brightness
inc appearance of strong echo signals
dec appearance of weak echo signals
dec appearance of strong echo signals
A

dec appearance of weak echo signals

53
Q 
which of the following helps improve lateral res in b-mode?
inc bandwidth
focusing with an acoustic lens
inc aperture
inc dynamic range
beam steering
A

inc aperture

54
Q 
you obtain 3d sweep in axial plane are are viewing it in multi planar display. what orthogonal planes are displayed?
transverse and coronal
transverse and sagittal
oblique planes at 90 degrees
coronal and sagittal
oblique planes at 60 degrees
A

coronal and sagittal

55
Q 
which of the following helps to improve the elevation res in b mode?
inc transmit power
focusing with acoustic lens
inc bandwidth
inc dynamic range
beam steering
A

focusing with acoustic lens

56
Q 
which artifact commonly results in echoes filling lumen of small vessels?
refraction
mirror image
partial volume
range ambiguity
multipath
A

partial volume

57
Q 
which artifact results in axial and lateral displacement of a reflector?
multipath reflections
refraction
side lobe
partial volume
enhancement
A

multipath

58
Q 
what type of res is determined by number of pixels in scan converter?
spatial
temporal
contrast
elevational
all of the above
A

spatial

number of pixels inc, spatial res improves.

59
Q 
which artifact is related to beam attenuation
comet tail
enhancement
aliasing
reverberation
side lobe
A

enhancement

enhancement occurs distal to a structure that has less attenuation of the sound beam compared to surrounding tissue

60
Q 
improve border definition by ?
use lower line density
use spatial compound imaging
use 2d array transducer
apply speckle reduction algorithm
use frame avg
A

use spatial compound imaging

61
Q 
propagation speed error results in:
improper axial pos of echo
improper lateral pos of echo
shadowing behind echo
enhancement behind echo
none of the above
A

improper axial pos of echo

62
Q 
you are observing sonographic artifact ased on interference patterns of scattered echoes:
mirror
acoustic speckle
grating lobe
comet tail
refraction
A

acoustic speckle

63
Q 
complete destructive interference of echo reflections will affect the display in the following way:
white pixel
dark gray pixel
black pixel
light gray pixel
none of the above
A

black pixel

64
Q 
inc both imaging depth and scan line density results in:
reduced contrast res
improved axial res
reduced temp res
reduced lateral res
all of the above
A

reduced temporal res

greater imaging depth and scan line density decreased the frame rate; axial and contrast res are not affected; inc scan line density will improve lateral res

65
Q 
inc number of acoustic scan lines in one frame improves:
lateral res
temporal res
axial res
elevational res
contrast res
A

lateral res

number of lines in frame inc, distance b/w lines decreases; reducing the dist improves lateral res

66
Q 
what component is necessary for real time b mode scanner but not present in a mode?
scan converter
clock
transmitter
transducer
receiver
A

scan converter

67
Q 
which is the best to demonstrate tissue boundaries that are not perpendicular to sound beam?
speckle reducing algorithm
persistence
spatial compound
panoramic imaging
tgc
A

spatial compound

method which sound beam is steering in multiple directions by employing time delays

Physic Principles (4 decks)

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